Hermetically sealed crystal



July 4,- 1950 P. R. HOFFMAN l 2,513,870

HERMETICALLY SEALED CRYSTAL Filed Jan. 23, 1948 INVENTOR /D/n//p f?.Hof/Cm cm BY I /m/ @uw y Mci A WMA/YJ Patented July 4, 1950 UNITEDSTATES PATENT OFFICE Application-January 23, 1948, Serial No. 3,939

Claims.

This invention relates to improvements in hermetically sealed electricalunits and relates more particularly to an hermetically sealed crystal ofthe xed frequency type.

The various objects and advantages of the in'- vention will be apparentand best understood from the following description and the accompanyingdrawings in which:

Fig. l is a side view in vertical section of a container embodying theinvention;

Fig. 2y is a section view taken along the line 2--f-2 of Fig. 1;

Fig. 3 is a top View of the container illustrated in Fig. 1;` and Fig. 4is a side view in section of a closure member for the containerillustrated in Fig, 1,

The importance of hermetically sealing electrical units so that theelectrical .elements will be protected from changes in atmosphericconditions, such as moisture, that will aiect their electricalcharacteristics and proper performance is well known.` One method ofconstructing an hermetically sealed container is illustrated in PatentNo. 2,057,790. In Such a construction the end closure pieces for thecontainer have a resilient material such as rubber on their outersurfaces and the ends of the container are crimped or spun over so thatthe turned-in end of the container presses into the resilient materialto form the seal. In this type of construction the entire periphery ofthe end of the container must be brought into engagement with theresilient material in order to form an effective seal. This makes itnecessary to have special jigs or spinning tools to perform thisoperation and generally limits the shape of the container that may beused to a cylindrical container because of the nature of the closureoperations required. In addition, such an operation must be carefullyperformed since even the smallest opening between the end of thecontainer and the resilient material will destroy the effectiveness ofthe seal.

An hermetic seal may be obtained in accordance with the presentinvention with practically any shape of container and the closure may beeffectively made on an ordinary press. The necessity for bringing theentire edge of the container into contact with the outer surface of theend closure is eliminated and pressure on the end closure at a fewspaced points will insure a proper seal.

In a container embodying the present invention, as illustrated, there isa container Ill made of a suitable material such as brass, aluminum, orthe like. The container ID illustrated is oval in shape and is closed atone end. The container is open at its other end so that a crystal I Imay be placed inside of the container. The crystal II is of the fixedfrequency type and isr supported by wire clips I2 and I3 that are inturn supported from the end closure I4.

The ends .of the wire clips I2 and I3 holding the crystal II contact`conductors I5 and I6 respectively that extend along opposite sides oithe crystal II. The other ends of the Wire clips I2 and I3 are solderedto eyelets or rivets I l 4and I8, respectively. The eyelets Il and IBextend through the end closure I4 and 4Serve as wiring terminals towhich lead wires `I9 and 2,0- Inay ,be aiiixed.

The end closure I4 is laminated and has a rigid insulating material 2lsuch as a molded .synthetic resi-n, or the like' on one side `and aresilient insulating material 22 such asa synthetic rubber oi thechlorobutadiene polymer type or the like on its other side.

The open end of the container is Somewhat enlarged to accommodate the'laminated end closure. The end closure I4 is fitted into the containerwith the resilient material 212 resting on a lip 23 formed by adownwardly and outwardly sloping shoulder 23a. The lip 23 extends aroundthe inside of the container and supports the end closure inside of thecontainer. When the end closure has been placed in the container, theend of the container is crimped or pressed over the edges of the endclosure to hold the end closure in the container. The turned over edgesof the container engage with and press against the rigid outer surfaceof the end closure. This forces the resilient material 22 into contactwith the entire periphery of the lip 23 and also with the inclinedshoulder 23a hermetically sealing the container.

The hermetic seal obtained in this manner is not affected if the end ofthe vcontainer does not engage the end closure around its completeperimeter. In fact it is sufcient if the end of the container engageswith the end closure I4 at a few spaced points as this will force theresilient material 22 into engagement with the lip 23 and the shoulder23a at all points. Thus, by this arrangement an effective seal may beobtained regardless of slight irregularities or variations in the mannerthat the end of the container engages with the end closure.

When the end closure is secured in place, the resilient material 22iiows along the inclined shoulders 23a as indicated at 24. This flowingof the resilient material not only forms a highly effective hermeticseal, but is also provides a gripping action that prevents breaking ofthe seal by shrinkage or sagging of the end closure. The eyelets 'I 'land I8 forming the terminals for the electrical connections are alsopressed into the resilient material so that they are effectively sealedagainst leakage of moisture or air.

l An hermetically sealed container made in accordancewith the presentinvention not only may be made in any shape desired, but it is alsovextremely economical to manufacture as the unit may be assembledWithout special jigs 0r tools.

It will be apparent that sucha container may be used for any type ofelectrical unit desired and it will be understood that various changesmay be made in the embodiment of the invention that has been illustratedand described Without departing from the scope of the invention asdefined by the appended claims.

I claim: i

l. In an hermetically sealed electrical unit the combination of acontainer, said container having `an opening at one end thereof, aninclined internal shoulder extending around the in- -side of thecontainer and an end closure of insulating material fitted into saidcontainer and `being supported on a lip formed by the inclined shoulder,said end closure having a resilient material on its inner surface and arigid material on its outer surface and the edges at the end of thecontainer being turned .over the edge of the 4end closure to hold theclosure in place and the resilient material in engagement With the4internal lip and shoulder. Y

2. An hermetically sealed electrical unitas defined in claim 1 whereinthe end closure serves as a support for an electrical element enclosedin the container and Wiring terminals extend through the end closure;

3. An hermetically sealed electrical unit as defined in claim 1 whereinthe resilient material on lthe end closure is synthetic rubber likematerial.

4. An hermetically sealed crystal of the fixed frequency type comprisinga container, said container having `an opening at one end thereof, an

4 inclined internal shoulder extending 'around the inside of thecontainer, an end closure of insulating material fitted into thecontainer and resting on a lip formed by said inclined shoulder, saidend closure having an inner surface of resilient material engaging withsaid lip and an outer surface of rigid material, the edges of the end4of the container being turned iniand engaging with the `outer vsurfaceof the end closure, terminals extending through the end closure and acrystal of the ixed frequency type connected to and supported from saidterminals.

5. In a hermetically sealed electrical unit the combination of acontainer, said container having an opening at one end thereof, aninternal shoulder extending around the inside of the container at itsopen end with `said shoulder being spaced from the end of the container,an end closure of insulating material tted into the open end of saidcontainer and resting on said shoulder, said end closure consisting ofan outer member of. rigid material and an inner member of resilientmaterial, inwardly extending portions carried by said container at ,itsopen end, said inwardly extending portions extending over and engagingwith the rigid outer member of the end closure and urging the resilientinner member of the end closure into sealing engagement with theinternal shoulder of the containerand an electrical terminal extendingthrough said end closure, said electrical terminal having a flangedportion in sealing engagement-With the resilientinner member. of theendv closure.

PHILIP R. HOFFMAN.

REFERENCES errno The following references are of record in the file ofthis patent: y y

OLarte et al. Dec. 16, 1947

